The last unit that came down for annual maintenance was unit 1. We did the usual: set up all the lighting and map out any cavitation that is found in the unit. However, last year a crack in the liner was repaired - a huge job that requires an engineered procedure. We went into this unit presuming that the crack would resurface, so we arranged for an engineer to do a dye penetrant test on the liner where the crack had been repaired to ensure there was no further cracking. Luckily for us, the repair from last year held up. The cavitation was fairly severe in other locations on the runner and on the liner, so we decided to do the repairs this year.

During maintenance on unit 4, we came across some problems electrically with the unit. This lead to a longer outage period and many man hours to get the unit back up and running. I tried to learn as much as time permitted regarding the repairs; however it was a lot to take in when you’re a welder - not an electrician or engineer.

My role during this repair was to sweat off horse shoe connectors to allow a piece of the unit called the “pole” to be removed. There were several poles that were damaged; therefore there were several horse shoe connectors which needed to be removed in order to proceed with the repairs.

This was a first-of-its-kind job for me, so with the help of an electrician we began to tackle the work.

This is what the horse shoe connectors look like prior to removing them.

We had to be sure we covered up the area around the bolts so we didn’t heat them up with the torch and damage them.

We used a set of oxy acetylene torches to sweat off the bolts as they were soldered on.

We had to carefully heat up the bolts with the torch just enough to melt the solder.

The bolts were then removed with wrenches, with care not to drop any bolts down between the poles as they all need to be recovered prior to starting up the unit again as a safety precaution.

We then had to re-tin the ends of the horse shoe connectors in preparation for reinstalling them; you do this by heating the ends and quickly wiping off the excess solder.

This is what the location of the horse shoe connectors looks like after the removal.

I have successfully made the four-hour drive down Hwy 6 to Grand Rapids, Manitoba. After an afternoon of unpacking and settling in, I was ready for my first day at a generating station. Having never worked in a GS before, there is a lot to learn. Thankfully Grand Rapids is on the smaller side, and I caught on fairly quickly.

During my rotation up here, I will be working primarily in the control room. Our duties during the day and night shift are station rounds, and to investigate any alarms that come in. Rounds include a walk around the entire plant, inside and out, recording hour readings, checking oil levels, and most importantly, making sure excessive water isn’t finding its way into places it shouldn’t be.

While doing the rounds on my third shift, I noticed some sparking on the brushes in Unit 1. (Brushes are one of the main components used to transfer the current from the generator to power lines) We ended up having to take it out of service to investigate the problem. This was a great opportunity for me to get my hands dirty (literally), because the unit was completely de-energized, and the brakes were put on. Here is what the generator looks like:

This is where the mechanical energy (the turbines rotating through the water) is converted to electrical energy. Normally, this part of the unit is spinning. I noticed the sparking on the top two silver coloured rings. The remedy was to reverse the polarity of the slip rings, and so far, no more sparking has been noted.